A wide range of security services may be available to applications in a heterogeneous computer network. Resource Management Systems (RMSs) responsible for assigning computing and network resources to tasks need to know the resource-utilization costs associated with the various network security services. In order to understand the range of security services and RMS needs to manage, a preliminary security service taxonomy is defined. The taxonomy is used as framework for a preliminary method for defining the costs associated with network security services.